The present invention relates to a coffee powder metering device for coffee vending machines comprising in a structure: a tubular main part, formed by two opposite side panels and two walls, perpendicular to the side panels; an end wall for closing off one end of the tubular main part, opened by power means; and a thrust wall inside the tubular main part, opposite the end wall and set at an adjustable distance from the end of the tubular main part towards which it is moved by control means. The tubular main part, end wall and thrust wall form a compartment for receiving a given quantity of coffee power, through an inlet in one of the sides, and forcing it out through the end by means of the thrust wall.
Although they offer a number of advantages from certain points of view, known metering devices currently being used all have the following drawback in common.
It is practically impossible to ensure that the thrust wall, which forces the coffee powder out as it slides down the tubular main part, mates perfectly all the way round with the tubular main part, the result is that, however small, at least part of the edge of the thrust wall does not contact the tubular main part.
Because of this gap, the thrust wall does not force out all the coffee powder in the compartment and a small amount, corresponding to the size of the gap, is left, on account of its oily nature, on the wall of the tubular main part.
The aim of the present invention is to provide a metering device designed structurally and functionally to overcome the defect of known systems.